Add as many as possible Speech-To-Text audio file input formats.

Currently IBM Watson Speech to Text service supports only “ogg” compressed format. However, a new standard for WebRTC platform is “webm”. As a result, WebRTC could be either used with Firefox only or client browser should send huge “wav” files without compression to Bluemix. Since adding support of new audio format for the STT server is trivial, please add as many compressed formats as possible (at least formats that are not restricted by some license).